This invention relates generally to key, lock, and key and lock systems.
Keys and locks are well understood in the art. Typically, a key will include a key grip head that can be held and readily manipulated by a human hand, and a key shank attached to the key grip head (those skilled in the art will sometimes refer to a key shank as being comprised of both a shank portion and a bit portion; as used herein, the term xe2x80x9cshankxe2x80x9d shall be understood to refer to both of these segments). The key shank fits within a corresponding keyed lock cylinder such that, when the key shank comprises an appropriate match to the configuration of the keyed lock cylinder, the key grip head can be rotated, thus causing a mechanism within the keyed lock cylinder to rotate correspondingly and either engage or disengage a corresponding locking mechanism.
As an added security measure, it is also known in the art to combine such a key with a key mounted transceiver that inductively transceives information, using radio frequency magnetic fields, with a reader. For example, some vehicles provide such a key that inductively communicates with a reader that is mounted within the dashboard of the vehicle. These systems transfer energy from the reader to the key mounted transceiver through an air coupled transformer comprised of two inductive elements (each being an antenna), one being mounted in the dashboard and the other in the key mounted transceiver. The inductive antenna (often a coil) of the key mounted transceiver forms a part of a tuned, or resonant, circuit. The inductive antenna of the reader may also form part of the tuned circuit. Such tuned circuits are required to maximize the energy that is coupled to the key mounted transceiver. In accordance with well understood prior art technique, each such tuned circuit comprises at least a capacitor and coil.
Precise control of the tuned circuit elements and the powering frequency are required to assure reliable system operation which causes a corresponding increase in associated product costs. Further, because of antenna size requirements, typical prior art solutions use a ferrite-based antenna to minimize the antenna size. Such materials change in permeability when subjected to mechanical stress. When forming the key grip head using plastic overmolding techniques, mechanical stress can be imposed upon the ferrite antennas that will result in substantial changes in inductance. This can adversely effect the tuned circuit and degrade system performance. Additional mechanical stresses can occur because of temperature changes and the large thermal coefficients of expansion that are experienced during overmolding processes. Because of this, typical prior art key transceivers use transceivers that are encapsulated in glass tubes that can be inserted into the key grip head after the overmolding process to eliminate mechanical stress. This again can significantly increase cost. And, of course, magnetic coupling as relied upon by such an approach can be adversely effected by the presence of metal in the key shank, the lock cylinder or other proximal materials, which can effect cost of a reliable configuration, range, and so forth.
There exists a need for a key, lock, and key and lock system that at least avoids in part some or all of these prior art difficulties.